NCR RealPOS 50 - ACPI Processor C-States

Product Overview 1-21
ACPI Processor C-States
ACPIdefinesthepowerstateofsystemprocessorswhileintheG0workingstateas
beingeitheractive(executing)orsleeping(notexecuting).Processorpowerstatesare
designatedC0,C1,C2,C3,…Cn.
TheC0powerstateisanactivepowerstatewheretheCPUexecutesinstructions.The
C1throughCn
powerstatesareprocessorsleepingstateswheretheprocessor
consumeslesspoweranddissipateslessheatthanleavingtheprocessorintheC0
state.
Whileinasleepingstate,theprocessordoesnotexecuteanyinstructions.Each
processorsleepingstatehasalatencyassociatedwithenteringandexitingthat
corresponds
tothepowersavings.Ingeneral,thelongertheentry/exitlatency,the
greaterthepowersavingswheninthestate.
Toconservepower,OSPMplacestheprocessorintooneofitssupportedsleeping
stateswhenidle.WhileintheC0state,ACPIallowstheperformanceoftheprocessor
tobealtered
throughadefinedʺthrottlingʺprocessandthroughtransitionsinto
multipleperformancestates(P‐states).
Note: The7611AtomN270ProcessorsupportsC0andC1states.Supportofdeeper
sleepstatesisnotrequiredduetoitsinherentlylowpowerconsumption.